Fan grill construction

ABSTRACT

Improved fan grill/guard construction for fans for supplying air, where the fan has a front grill with an outer ring which wraps around and is dimensionally structured to improve airflow and to diffuse the air over a wide area.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to an improved fan grill guard construction ofthe type where the grill has an outer ring, which is dimensionallystructured to provide greater airflow and diffusion.

2. Description of the Prior Art

The typical grill used on the front of oscillating, pedestal or wallmount fans is of round wire, with some fans such as shown in U.S. Pat.No. 6,071,079 having a front grill of molded plastic. There are manyadvantages in using molded plastic grills, in that plastic does notrust, is inexpensive to mold and does not require welding or painting.In addition, plastic permits easy design variation to achieve a lookthat is less restrictive in the center, and allows the customer to seethe blades.

Plastic grills can also be constructed so they do not require additionalparts such as rings or clips for assembly.

While the prior art, U.S. Pat. No. 6,071,079, uses plastic grills, it isdesigned to provide a focused air pattern, which is not entirelysatisfactory if used in an oscillating fan, as it results in an on-offair flow, which is not as desirable as a diffused air flow, which isobtained by the grill construction described herein.

SUMMARY OF THE INVENTION

It has now been found that an improved fan grill construction can beobtained for a front grill, which has an outer ring which isdimensionally structured so that the air flow is diffused instead offocused, resulting in an improved total air volume (NEMA CFM) over alarger area.

The principal object of the invention is to provide front grillconstruction for a fan that is dimensionally structured to provideincreased air volume over a large area.

A further object of the invention is to provide fan grill constructionthat allows tighter spacing to the fan blade periphery to provide a moreefficient package with improved safety.

A further object of the invention is to provide fan grill constructionwhich adds mass to the outside of the grill to dampen vibration.

A further object of the invention is to provide a front grill which isconstructed for molded plastic.

A further object of the invention is to provide a fan grill constructionthat can be adapted to a variety of types and sizes of fans.

A further object of the invention is to provide fan grill constructionwhere the grill is not part of the support for the motor/blade assembly.

Other objects and advantageous features of the invention will beapparent from the description and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The nature and characteristic features of the invention will be morereadily understood from the following description taken in connectionwith the accompanying drawings forming part hereof in which:

FIG. 1 is an exploded perspective view of a prior art fan;

FIG. 2 is an exploded perspective view of a fan with the new front grillconstruction of the invention;

FIG. 3 is a horizontal sectional view of the assembled prior art fan ofFIG. 1;

FIG. 4 is a view similar to FIG. 3 but showing the improved fan grillconstruction of the invention, and

FIG. 5 is a graph comparing the performances of the prior art fan grillconstruction to the improved fan grill construction of the invention.

It should, of course, be understood that the description and drawingsherein are merely illustrative and that various modifications andchanges can be made in the structures disclosed without departing fromthe spirit of the invention.

Like numerals refer to like parts throughout the several views.

DESCRIPTION OF THE PREFERRED EMBODIMENT

When referring to the preferred embodiment, certain terminology will beutilized for the sake of clarity. Use of such terminology is intended toencompass not only the described embodiment, but also technicalequivalents which operate and function in substantially the same way tobring about the same result. dimension C is the width of ring 70. Thedimension D is the diameter of the blade assembly 54.

Referring now more particularly to FIGS. 1 and 3 of the drawings, atypical prior art fan 10 is illustrated. The fan 10 includes an electricmotor housing 11, which contains an electric motor (not shown) of wellknown type, which may be connected to a source of electrical power (notshown). The fan motor has an output shaft 12 with a hub 14 of bladeassembly 15 attached thereto, with three blades 16 being shown.

The fan motor housing 11 may be mounted to a yoke (not shown) which maybe mounted to a pedestal (not shown) or other well known supportstructure, which can rest on the floor, on a table or otherwhere asdesired. The housing 11 has a rear grill 17 mounted thereto, which is ofcircular configuration, with a plurality of spaced radial ribs 18,connected to a plurality of concentric rings 19, with the radial ribs 18extending out to a circumferential rim 20 and inwardly to a center ring21. A front grill 25 is provided, which has a plurality of spaced radialribs 26, which are connected to a plurality of concentric rings 27. Theribs 26 extend out to an outer rim 28, which mates with rim 20 of reargrill 17.

The radial ribs 26 also extend inwardly and are connected to a centerplate 29.

Both the front and rear grills 25 and 17 are preferably formed of moldedplastic.

As shown in FIG. 3, the arrows 30 illustrate the airflow through therear grill 17, and out the front grill 25 in a focused pattern, whichupon oscillation provides the on-off airflow that is not desirable.

Referring now more particularly to FIGS. 2 and 4, the improved frontgrill construction is therein illustrated and as part of a fan 50.

The fan 50 includes an electric motor housing 51, which contains anelectric motor (not shown) of well known type which may be connected toa source of electrical energy (not shown). The fan motor has an outputshaft 52, to which a hub 53 of a blade assembly 54 is attached, with theblade assembly having three blades 55.

The fan motor housing 51 may be mounted to a pedestal (not shown) orother structure as described for fan 10.

The motor housing 51 has a rear grill 57 mounted thereto in conventionalmanner such as by bolts (not shown).

The rear grill 57 has a plurality of concentric rings 58 to which spacedinterrupted radial ribs 59 and 60 are connected. The ribs 59 are shorterthan ribs 60 and extend out to a rim 62 of grill 57. The ribs 60 extendout to rim 62 and inwardly to a center ring 63 which is attached tomotor housing 51.

A front grill 65 is provided, of circular configuration, with aplurality of concentric rings 66, which have a plurality of spacedradial ribs 67 and 68 connected thereto, with ribs 67 extending inwardlyto a center plate 69, and outwardly to a ring 70 to be described.

The ribs 68 extend outwardly to ring 70, and inwardly short of plate 69.

The ring 70 includes a curved panel 71, which extends inwardly to aninclined panel 72, and outwardly to a rim 73. The rim 73 mates with rim62 of grill 57 with spaced tabs 62 A therearound, which are engaged withslots 74 in rim 73 to retain the grills 57 and 65 together.

In FIG. 4, the ring dimensions are indicated by the letters A, B, C andD. The dimension A is the distance from the tip 75 of a blade 55 to theinside diameter of the ring 70. The dimension B is the depth of ring 70,or the distance from the rear most portion of rim 73 to the front end ofpanel 71. The

The dimensions A, B, C and D for the fan 50 in the preferred embodimentfor a 16 inch fan with blade diameter D=16 inches, are A=0.170 inches,B=1.41 inches and C=0.95 inches.

The dimensions A, B, and C for oscillating fans with a typical bladediameter from 6 to 30 inches, with D as an initial dimensional basepoint, have the dimensions calculated as follows where the range of A is+/−40% of D as measured from tip 75, B=0.60 to 4.5 inch, and C=40 to200% B.

It has been found by testing that a 16 inch fan 50 with a front grill65, compared to a prior art 16 inch fan 10 with front grill 25, providessignificant improvement.

The fan 50 on high speed at 9 feet from the fan provided an air velocity(NEMA CFM) of 5710.00, whereas fan 10 provided an air velocity (NEMACFM) of 4737. 10.

Referring to FIG. 5 tests were run on two fans comparing the fans 10 and50 with measurements at horizontal distances to 34 inches on each side.The results were plotted in in FIG. 6 which shows significantly greaterair velocities over the distance for fan 50 with the improved frontgrill construction.

It will thus be seen that an improved fan grill construction has beenprovided with which the objects of the invention are achieved.

1. In combination with a fan, which fan has a fan motor, a fan bladeassembly attached to and driven by said fan motor, a motor housingcontaining said motor, a rear grill to which said motor housing ismounted, and a front grill attached to said rear grill, the improvementwhich comprises, a plurality of spaced radial ribs, said front grillhaving a center plate to which some of said radial ribs are connected,at least a portion of said radial ribs extending outwardly to acircumferential ring, said circumferential ring having a curved panelextending to a rim and an inclined panel to which said ribs areconnected , said ribs connected to said inclined panel, saidcircumferential ring having dimensions based on a fan blade diameter D,with a dimension A of said ring being a distance from a tip of said fanblade assembly to an inside diameter of said ring, a dimension B being adepth of said ring, and a dimension C being a width of said ring, saiddimension A being up to about 40% of said fan blade diameter D, saiddimension B being between about 0.60 to 4.5 inches and said dimension Cis between about 40 to 200% of said dimension B, and wherein said frontgrill provides a diffuse airflow from said fan.
 2. A fan as defined inclaim 1 in which D is 16 inches, A is 0.170 inches, B is 1.41 inches andC is 0.95 inches.
 3. A fan as defined in claim 1 in which said frontgrill is of molded plastic.
 4. A fan according to claim 1, wherein saidfront grill provides an increased air volume over a predetermined area.5. A fan according to claim 4, wherein said fan is an oscillating fan.6. A fan according to claim 5, wherein said motor housing is external tosaid rear grill.
 7. A fan according to claim 1, wherein said front grilldampens vibrations of said fan based on a mass of said front grill.
 8. Afan according to claim 1, wherein an inside edge of said circumferentialring overlays a portion of said fan blade by said dimension A.
 9. A Thefan according to claim 1, wherein an inside edge of said circumferentialring establishes a clearance from said fan blade tip by said dimensionA.
 10. A front grill for use with an oscillating fan having a fan bladeassembly, said front grill comprising: a circumferential ring at anouter periphery of said front grill, said circumferential ring having aninside edge spaced away from a tip of said fan blade assembly by apredetermined distance based on a diameter of said fan blade assembly,said front grill providing a diffuse air pattern.
 11. The grillaccording to claim 10, wherein said predetermined distance is less thanabout 40% of a diameter of said fan blade assembly, and saidcircumferential ring further comprising: i) a depth, and ii) a width,wherein said depth is between about 0.60 and 4.50 inches, and said widthis between about 40% to 200% of said depth.
 12. A grill for use with afan having a motor and a fan blade assembly, said grill comprising: acircumferential ring at an outer periphery of said grill, saidcircumferential ring having: i) an inside edge spaced away from a tip ofsaid fan blade assembly by a predetermined distance, where saidpredetermined distance is less than about 40% of a diameter of said fanblade assembly, ii) a depth, and iii) a width, wherein said depth isbetween about 0.60 and 4.50 inches, said width is between about 40% to200% of said depth, and said inside edge of said circumferential ringoverlays a portion of said fan blade assembly by said predetermineddistance and wherein said grill provides a diffuse airflow from saidfan.
 13. A grill according to claim 12, wherein said grill provides anincreased air volume over a predetermined area.
 14. A grill according toclaim 12, wherein said fan is an oscillating fan.
 15. A grill accordingto claim 12, wherein said fan is a table mounted fan.
 16. A grillaccording to claim 12, wherein said fan is a floor mounted fan.
 17. Agrill according to claim 12, wherein said grill dampens vibrations ofsaid fan based on a mass of said grill.
 18. A grill according to claim12, further comprising a plurality of attaching means for coupling saidgrill to a portion of said fan.
 19. A grill according to claim 18,wherein said attaching means is a plurality of slots formed in saidcircumferential ring.
 20. A grill according to claim 12, wherein saidgrill is mounted on a front portion of said fan such that air circulatedby said fan blade exits through said grill.
 21. A grill according toclaim 12, wherein said grill is a plurality of grills, a first one ofsaid plurality of grills mounted on said fan motor on a front portionthereof, such that air circulated by said fan blade enters through saidfirst grill, and a second one of said plurality of grills mounted on afront portion of said first grill such that air circulated by said fanblade exits through said second grill.
 22. A grill according to claim12, further comprising a rear grill coupled to said grill and whereinsaid motor is mounted external to said rear grill.
 23. An oscillatingfan having a rear grill, a front grill attached to said rear grill, afan motor external to said rear grill, to which said rear grill ismounted, a fan blade assembly attached to and driven by said fan motor,said front grill comprising: a circumferential ring at an outerperiphery of said front grill, said circumferential ring havingdimensions based on the fan blade assembly having a diameter of about 16inches: i) an inside edge spaced away from a tip of said fan bladeassembly by about 0.170 inches, establishing a clearance between saidfan blade assembly tip and said inside edge of said circumferentialring, ii) a depth of about 1.41 inches, and iii) a width of about 0.95inches, wherein said front grill provides a diffuse airflow from saidfan.
 24. A grill according to claim 23, wherein said fan is a tablemounted fan.
 25. A grill according to claim 23, wherein said fan is afloor mounted fan.
 26. A grill for use with a fan having a motor and afan blade assembly, said grill comprising: a circumferential ring at anouter periphery of said grill, said circumferential ring having: i) aninside edge spaced away from a tip of said fan blade assembly by apredetermined distance, where said predetermined distance is less thanabout 40% of a diameter of said fan blade assembly, ii) a depth, andiii) a width, wherein said depth is between about 0.60 and 4.50 inches,said width is between about 40% to 200% of said depth, and said insideedge of said circumferential ring one of i) overlays a portion of saidfan blade assembly by said predetermined distance and ii) establishes aclearance from said fan blade assembly tip by said predetermineddistance and wherein said grill provides a diffuse airflow from saidfan.
 27. A grill according to claim 26, wherein said grill provides anincreased air volume over a predetermined area.
 28. A grill according toclaim 26, wherein said fan is an oscillating fan.
 29. A grill accordingto claim 26, wherein said fan is a table mounted fan.
 30. A grillaccording to claim 26, wherein said fan is a floor mounted fan.
 31. Agrill according to claim 26, wherein said grill dampens vibrations ofsaid fan based on a mass of said grill.
 32. A grill according to claim26, further comprising a plurality of attaching means for coupling saidgrill to a portion of said fan.
 33. A grill according to claim 32,wherein said attaching means is a plurality of slots formed in saidcircumferential ring.
 34. A grill according to claim 26, wherein saidgrill is mounted on a front portion of said fan such that air circulatedby said fan blade exits through said grill.
 35. A grill according toclaim 26, wherein said grill is a plurality of grills, a first one ofsaid plurality of grills mounted on said fan motor on a front portionthereof, such that air circulated by said fan blade enters through saidfirst grill, and a second one of said plurality of grills mounted on afront portion of said first grill such that air circulated by said fanblade exits through said second grill.
 36. A grill according to claim26, further comprising a rear grill coupled to said grill and whereinsaid motor is mounted external to said rear grill.
 37. A fan comprising:a fan blade assembly having a diameter D; a motor assembly used torotate said fan blade assembly, said motor assembly comprising: anelectric motor; and a motor housing substantially enclosing saidelectric motor; a grill assembly comprising: a unitary front grillformed of a polymer, said unitary front grill comprising: a front centerportion; an integral front circumferential ring formed of a polymer,said front circumferential ring further comprising: a dimension B beingan axial thickness of said integral front circumferential ring, adimension C being a width of said integral front circumferential ringmeasured radially from an inside edge portion of said integral frontcircumferential ring to an outer periphery portion of said integralfront circumferential ring, and a plurality of front grill elementsdisposed between said front center portion and said frontcircumferential ring; and a rear grill coupled between said motorassembly and said unitary front grill, said rear grill comprising: arear center portion defining an aperture for receiving at least aportion of said motor assembly, said rear grill being detachably coupledto said motor assembly and a substantial portion of said motor assemblyremains external of said rear grill when said portion of said motorassembly is received by said aperture; an outer rim, and a plurality ofrear grill elements disposed between said rear center portion and saidouter rim, wherein a dimension A is a distance from a tip of said fanblade assembly to said inside edge portion of said integral frontcircumferential ring, and said dimension A is up to about 40 % of saiddiameter D, said dimension B is between about 0.6 inches and about 4.5inches, and said dimension C is between about 0.24 inches and about 9inches; and wherein said front grill provides a diffuse airflow fromsaid fan.
 38. The fan of claim 37 wherein said outer rim of said reargrill is a rear circumferential ring, and an axial thickness of saidrear circumferential ring combined with said dimension B defines acombined axial thickness of said grill assembly.
 39. The fan of claim 38wherein said combined axial thickness is between about 1 inch and about4.5 inches.
 40. The fan of claim 38 wherein said combined axialthickness is between about 1.4 inches and about 4.5 inches.
 41. A fancomprising: a fan blade assembly having a diameter D; a motor assemblyused to rotate said fan blade assembly, said motor assembly having anelectric motor and a motor housing substantially enclosing said electricmotor; a grill assembly comprising: a unitary front grill formed of apolymer, said unitary front grill comprising: a front center portion; afront circumferential ring formed integral with said front grill; and aplurality of front grill elements disposed between said front centerportion and said integral front circumferential ring, where openings aredefined between said front grill elements allowing air to passtherethrough, a dimension A being a distance from a tip of said fanblade assembly to an inside edge portion of said integral frontcircumferential ring, a dimension B being an axial thickness of saidintegral front circumferential ring, a dimension C being a width of saidintegral front circumferential ring measured radially outward from afurthest radial extent of said front grill elements to an outerperiphery of said integral front circumferential ring, and saiddimension A being up to about 40 % of said diameter D, and saiddimension C being between about 0.24 inches and about 9 inches, whereinsaid front grill provides a diffuse airflow from said fan, a rear grilladapted to be coupled to said unitary front grill, said rear grillcomprising: a rear center portion defining an aperture for receiving aportion of said motor assembly, said rear grill being detachably coupledto said motor assembly and a substantial portion of said motor assemblyremains external of said grill assembly when said portion of said motorassembly is received by said aperture, an outer rim, and a plurality ofrear grill elements disposed between said rear center portion and saidouter rim, where openings are defined between said rear grill elementsallowing air to pass therethrough.
 42. The fan of claim 41 wherein saiddimension B is between about 0.6 inches and about 4.5 inches.
 43. Thefan according to claim 37 or 41 wherein said inside edge portion of saidintegral front circumferential ring either (i) overlays a portion ofsaid diameter D of said fan blade assembly by said dimension A; or (ii)establishes a radial clearance from said tip of said fan blade assemblyby said dimension A.
 44. The fan according to claim 37 or 41 wherein amass of said integral front circumferential ring dampens vibration ofsaid fan.
 45. The fan according to claim 37 or 41 wherein said frontgrill elements further comprise a plurality of radial ribs, one or moreof said radial ribs extending from said integral front circumferentialring to said front center portion.
 46. The fan of claim 45 wherein oneor more of said radial ribs extend from said integral frontcircumferential ring towards, but short of, said front center portion.47. The fan of claim 37 or 41 wherein said rear grill is formed of apolymer and said rear grill elements comprise a plurality of radialribs, one or more of said radial ribs extending from said outer rim tosaid rear center portion.
 48. The fan of claim 47 wherein one or more ofsaid radial ribs extend from said outer rim towards, but short of, saidrear center portion.
 49. A fan comprising: a fan blade assembly having adiameter D; a motor assembly used to rotate said fan blade assemblygenerating an axial air flow in a forward direction, said motor assemblycomprising: an electric motor; and a motor housing substantiallyenclosing said electric motor; and a grill assembly comprising: a reargrill comprising a rear center portion, a rear outer periphery, and aplurality of rear grill elements disposed between said rear centerportion and said rear outer periphery, said rear center portion definingan aperture for receiving a portion of said motor assembly, said reargrill being detachably coupled to said motor assembly such that asubstantially portion of said motor assembly remains external of saidgrill assembly when said portion of said motor assembly is received bysaid aperture; a unitary front grill formed of a polymer, said frontgrill being detachably coupled to said rear grill, said unitary frontgrill comprising a front center portion, an integral front outerperiphery, and a plurality of front grill elements disposed between saidfront center portion and said front outer periphery; a circumferentialring disposed between said front grill and said rear grill, at least aportion of said circumferential ring being unitary and integral to saidfront grill and/or both said front grill and said rear grill, saidportion of said unitary and integral circumferential ring correspondingto said front grill being at least partially located axially forward ofsaid rear grill, wherein said unitary and integral circumferential ringdefines a dimension A being a distance from a tip of said fan bladeassembly to a forward inside edge portion of said unitary and integralcircumferential ring, a dimension B being an axial thickness of saidunitary and integral circumferential ring measured from a forward edgeto a rear edge of said unitary and integral circumferential ring, and adimension C being a width of said unitary and integral circumferentialring measured radially from said forward inside edge portion of saidunitary and integral circumferential ring to an outer periphery portionof said unitary and integral circumferential ring, wherein saiddimension A is up to about 40 % of said diameter D of said fan bladeassembly, and wherein said front grill provides a diffuse airflow fromsaid fan.
 50. The fan of claim 49 wherein said dimension C is betweenabout 0.24 inches and about 9 inches.
 51. The fan of claim 49 whereinsaid dimension B is between about 0.6 inches and about 4.5 inches. 52.The fan according to claim 49 wherein said front grill elements furthercomprise a plurality of radial ribs, one or more of said radial ribsextending from said unitary and integral circumferential ring to saidfront center portion.
 53. The fan of claim 52 wherein one or more ofsaid radial ribs extend from said unitary and integral circumferentialring towards, but short of, said front center portion.
 54. The fan ofclaim 49 wherein said rear grill is formed of a polymer and said reargrill elements comprise a plurality of radial ribs, one or more of saidradial ribs extending from one of said rear outer periphery and saidunitary and integral circumferential ring to said rear center portion.55. The fan of claim 49 wherein one or more of said radial ribs extendfrom one of said rear outer periphery and said unitary and integralcircumferential ring towards, but short of, said rear center portion.56. The fan of claim 49 wherein said unitary and integralcircumferential ring further defines a sectional profile taken along aradial plane from a center of said unitary and integral circumferentialring, said sectional profile defining a first circumferential panelhaving at least one of a straight sectional profile or a curvedsectional profile.
 57. The fan of claim 56 wherein said sectionalprofile further defines a second circumferential panel extending from aforward edge of an inner circumferential portion of said firstcircumferential panel, said second circumferential panel extendinginwardly towards said front center portion of said unitary front grill,said second circumferential panel having at least one of a straightsectional profile or a curved sectional profile.
 58. The fan of claim49, wherein said forward inside edge portion of said unitary andintegral circumferential ring either (i) overlays a portion of diameterD of said fan blade assembly by said dimension A, or (ii) establishes aradial clearance from said tip of said fan blade assembly by saiddimension A.
 59. The fan according to claim 49 wherein a mass of saidunitary and integral circumferential ring dampens vibration of said fan.60. The fan according to claim 37, 41, or 49 wherein said dimension B isbetween about 1 inch and about 4.5 inches.
 61. The fan according toclaim 37, 41, or 49 wherein said dimension B is between about 1.4 inchesand about 4.5 inches.
 62. The fan according to claim 37, 41, or 49wherein said dimension D of said blade assembly is greater than about 12inches.
 63. The fan according to claim 37, 41, or 49 wherein saiddimension D of said blade assembly is greater than about 16 inches. 64.The fan according to claim 37, 41, or 49 wherein said front grillprovides diffuse air flow from said fan.
 65. The fan according to claim37, 41, or 49 wherein said fan is an oscillating fan.
 66. The fan ofclaim 65 further comprising a pedestal, said pedestal being used toelevate and support said fan in an upright position with reference to asupport surface.
 67. The fan according to claim 37, 41, or 49 whereinsaid front grill and said rear grill are detachably coupled to oneanother.
 68. The fan of claim 67 wherein said front grill and said reargrill may be manually assembled and disassembled to/from one anotherwithout tools.
 69. The fan of claim 67 wherein at least one of saidfront grill or said rear grill may be at least partially nested withinthe other of said front grill or said rear grill when said front grilland said rear grill are disassembled from one another, therebyfacilitating efficient packaging.
 70. The fan of claim 67 furthercomprising a connecting mechanism disposed between and connecting saidfront grill and said rear grill.
 71. The fan of claim 70 wherein saidconnecting mechanism comprises a plurality of tab portions extendingbetween said rear grill and said front grill, said plurality of tabportions being integral with, or coupled to, one of said rear grill andsaid front grill.
 72. The fan of claim 71 wherein said connectingmechanism further comprises a plurality of slots defined by the other ofsaid front grill and said rear grill, said slots corresponding in numberand location to said plurality of tab portions, said slots beingconfigured to receive said tab portions.
 73. The fan according to claim37, 41, or 49 wherein said motor assembly is detachably coupled to saidrear grill through engagement of a male threaded component with a femalethreaded component.
 74. The fan according to claim 37, 41, or 49 whereinsaid rear grill is separate and distinct from said motor housing. 75.The fan according to claim 37, 41, or 49 wherein said grill assembly isstructurally supported by said motor assembly.
 76. The fan according toclaim 37, 41, or 49 wherein said motor housing substantially enclosesall sides and ends of said electric motor.
 77. The fan according toclaim 37, 41, or 49 wherein said motor assembly is separate and distinctfrom said rear grill.
 78. The fan of claim 77 wherein said motorassembly is detachable from said rear grill, thereby facilitatingefficient packaging.
 79. The fan according to claim 37, 41, or 49wherein said front grill elements further comprise a plurality ofsubstantially concentric rings.
 80. The fan according to claim 37, 41,or 49 wherein said rear grill is formed of a polymer.
 81. The fan ofclaim 80 wherein said rear grill elements further comprise a pluralityof substantially concentric rings.
 82. The fan according to claim 1,wherein an inside edge of said circumferential ring overlays a portionof said fan blade by said dimension A.